The Company network administrator has entered the "auto qos voip cisco-phone" command on  switch R1.  What does this command do？（）

• A、It disables the trust boundary feature because the switch knows a Cisco IP phone is attached.
• B、The switch assigns a CoS value of 5 to incoming packets.
• C、If a Cisco IP phone is attached and removed， the switch continues to trust the CoS values as  long as the switch is not rebooted.
• D、It turns on STP to see if a Cisco IP phone is attached.
• E、If a Cisco IP phone is attached， the switch trusts the CoS.
• F、None of the other alternatives apply.